The regulation of synthesis of isoleucine and valine in Neurospora crassa will continue to be investigated. The research will be mainly directed toward a further analysis of the pyruvate-threonine yields valine and isoleucine complex in the mitochondria, the dependence of its integrity on respiration and oxidative phosphorylation, the regulation of threonine deaminase and the condition of the inner mitochondrial membrane. BIBLIOGRAPHIC REFERENCES: Martin, Charles E. and Robert P. Wagner. 1975. Two forms of a mitochondrial endonuclease in Neurospora crassa. Can. Journal of Biochem. 53:823-825. Sutton, H. Eldon and Robert P. Wagner. 1975. Mutation and enzyme function in humans. Annual Review of Genetics Vol. 9:187-212.